1. Field of the Invention
This invention relates in general to laminating machines and in particular to an improved machine for continuously laminating articles with plastic.
2. Description of the Prior Art
Machines used for laminating articles, such as menus, cards and the like, use a type of plastic that has a thermoplastic side, such as polyethylene, that melts at a lower temperature than the other side, which may be a polyester based material such as Mylar. The plastic is normally in thicknesses from 0.0015 inch to 0.018 inch. Normally the plastic is drawn in webs from supply rolls past heating means into pressure and pull rollers. The heating means causes the adhesive sides to become slightly fluent, and the pressure rollers bond the heated webs to the article, which is sandwiched between. The pull rollers maintain tension on the web and stretch it while fans mounted below hasten cooling. A laminating apparatus of this type is shown in U.S. Pat. No. 3,309,983.
In order to increase the linear speed of the web for faster laminating, the web must be heated more quickly and cooled more quickly. If cooling is insufficient to cause the plastic to set prior to contacting the pull rollers, then wrinkling occurs. Also in conventional laminating devices, cleaning rollers and threading new rolls of plastic are tedius operations since the pressure and pull rollers are spring biased together and have no means to hold them apart. In addition it is not possible to laminate a single side of an article since during the period before and after the insertion of the article, the hot adhesive on the web would adhere to the adjacent roller.